1) If you're just browsing the web, and don't need to look at any Flash sites, it’s hard to beat. Fast and smoothly intuitive. You can't switch pages as quickly as you can switch tabs on a standard web browser, though, which can be a little awkward at times. But the double-tap-to-zoom-text thing, borrowed from the iPhone, is brilliant. It makes the wonderful Readability and Safari 5’s Reader feature completely unnecessary.
2) Gmail on the iPad is very cool: a combination of the built-in Mail app’s two-pane system with Gmail’s conversation view.
3) If I end up using this thing much, other than for travel, it will probably be to make Keynote presentations for class. (And for class use more generally.) I’ve tried creating a few sample Keynotes, and moving content around — copying and pasting links and images, for instance — is pretty awkward right now: lots of tapping. But in this case I don't think it’s a design problem, but rather a UI I’m not really used to. I expect it will get better with time.
The question will be whether the portability and usability of the iPad make it worth my trouble to deal with an extra gadget, when I can just make Keynote presentations on my MacBook and carry that to class. Right now the iPad feels like it may be one gadget too many — but if (when?) Apple comes up with a way to transfer files seamlessly and wirelessly between Macs and iPads, via a Dropbox-like system, then we’ll be golden. I think we’re headed towards a time when people can have multiple devices that stay in constant sync with one another, so whichever one you happen to pick up will have the resources you need (adapted to the limitations of the device, of course). That’ll be a good day — at least for those who aren't worried about living in the Cloud.
4) The on-screen keyboard is okay, but awkwardly sized, as can be seen even in Apple’s promotional videos. It’s too big to type thumbstyle, too small to type conventionally (and there’s nowhere to rest your palms). So your hands have to hover over the screen and peck gently at the keyboard, like especially delicate little birds. I have an Apple Bluetooth keyboard, and that works fine, but you have to go into the Settings and pair it with the iPad, then unpair it when you’re done to reactivate the on-screen keyboard. That’s cumbersome.
There are no serious text-editing apps for the iPad; I wonder whether there ever will be. This is an issue for me because I detest proprietary text formats and avoid them at all costs. As I have noted before, I write almost everything in plain text with Markdown formatting, and since I wrote that earlier post I have pretty much abandoned Pages and write anything I need to print out in LaTex. Nothing about my research-and-writing workflow is compatible with the iPad, and I can't see that it ever will be.
5) As a book-reading device it has virtues and vices. I've used the Kindle app, and the size of the screen solves many of the Kindle's typographical nightmares, but the iPad is HEAVY. That becomes a real problem after a while. Reading with one hand is not an option for the long term unless you're wanting to body build as you read. The iPad’s highly reflective screen makes it impossible to read anything on it not only outdoors but any place where there’s strong direct light. Marco Arment nails these problems and others, but Marco is also the maker of Instapaper, one of the greatest web services evar, and Instapaper looks utterly magnificent on the iPad.
6) You can't use an iPad without hooking it up to another computer first, but this is just plain stupid.
Overall: it’s cool. It’s magnetically attractive. But it won't help me do much of what I need to do, and I kinda wish I didn't have it.